It is well known in the art that the Wurtz-type coupling of haloorganosilanes provides a useful synthetic route to polysilanes. For example, linear polysilanes can be prepared by the alkali-metal reductive coupling of dichloroorganosilanes and branched polysilanes can be prepared by the reductive coupling of trichloroorganosilanes.
However, only a limited number of amine-promoted coupling reactions of silanes are known in the art. These reactions are not generally useful for the preparation of polysilanes. For example, Kaczmarczyk et al. disclose the disproportionation of disilicon hexachloride in the presence of trimethylamine to yield either hexasilicon tetradecachloride (J. Amer. Chem. Soc. 82, 751, 1960) or pentasilicon dodecachloride (J. In org. Nucl. Chem. 17, 186-188, 1961), depending on the reaction conditions. Wiber et al. teach the synthesis of pentasilicon dodecachloride by treatment of disilicon hexachloride with trimethylamine using a modification of the reaction conditions described by Kaczmaryk et al. for the preparation of hexasilicon tetradecachloride (Angew. Chem. Int. Ed., 1, No. 9, 517, 1962).
The present inventors have discovered an amine-promoted coupling reaction of trichlorosilane that produces novel compounds containing a tetradecachlorocyclohexasilane dianion.